The capillary tube uses capillary action to draw the blood into the micro tube thereby eliminating the tendency for scooping. Because the capillary tube is also coated with anticoagulant, the blood sample begins mixing immediately with it. When filled end-to-end, the length of the capillary tube defines a specific amount of collected blood. This results in tissue-free samples, reduced clotting, accurate sample volume and ultimately, fewer redraws and increased patient comfort.

The attached cap is color coded to designate the type of additive that is in both the capillary tube and the micro tube. Since the cap is attached, the possibility of contamination or accidental loss is eliminated. The caps are pierce-able and available as self-sealing.

The micro tubes come in multiple sizes, a wide variety of additives and with, or without, gel separators. Printed on the micro tube are the lot number and expiration date as well as fill lines. There are also flat bottom versions and tube extenders for centrifuges available.